1. Provide an enclosed, barrier facility with controlled in and out sterilization for materials and supplies, in and out antibacteriological showers for personnel and laminar flow housing for breeding stock and experimental mice. 2. Provide a pyrogen-free, self-sustaining, unshared colony of athymic nude mice to be managed by scientific and technical staff. 3. Provide a colony population of post-weanlings totaling approximately 800-1000 athymic nude mice. These figures include 100-200 NU/NU weanlings monthly to the experimental pool from self-sustaining breeding stock, the breeding stock (approximately 150-200), and an experimental reserve pool (approximating 100-200 monthly). 4. Provide space, equipment, and supplies in the barrier facility for surgery, physical examinations, weighing, cobalt radiation of animals, and injecting the mice, and other necessary equipment including refrigerator, tissue culture hood, surgical instruments, analytical balance, and preparation of tissues for light and electron microscope examination, including paraffin embedding for routine histology. 5. Provide experienced staff with proven capabilities for performing animal surgery, long-term maintenance of experimental mice, preparation of tissues for high resolution microscopy. 6. Provide expertise in a variety of established procedures for performing xenografts, including implanting carcinogen-treated, and virally infected tissue. 7. Using protocols and human tissues provided by the NCI, inoculate, maintain, observe and examine nude mice host to document the growth and development of the implants. 8. Autopsy all animals found dead or sacrificed and prepare tissues for histological examination, providing approximately 1200 routine histological slides (h&e stained) per year, and other histological preparations as requested by the project officer. 9. Provide staff trained and experienced to use applicational development (ADL) and the interactive language DBASE IV for programming, storing, and communicating (as required) project data records by computer to the NCI.